System and method for detection of analytes in exhaled breath

ABSTRACT

A device, system, and methods are disclosed for detecting the presence or determining a quantitative amount of at least one drug substance from exhaled breath of a subject in-situ. A collecting surface has a Surface Enhanced Raman Spectroscopy (SERS)-active layer that comprises at least one SERS-active material. The collecting surface is arranged as an outer surface of a waveguide for contact with exhaled breath, such that at least traces of said at least one drug substance in said exhaled breath can contact said SERS-active layer for read-out of a Raman shift spectrum that is detected in-situ for said detecting the presence or determining the quantitative amount of said at least one drug substance from said exhaled breath.

FIELD OF THE INVENTION

This invention pertains in general to the field of systems and methodsfor collecting a sample from exhaled breath of a subject, and fordetecting the presence or determining the quantitative amount ofanalytes in the breath sample. The analytes are for instance drugsubstances in the exhaled breath. More particularly, the inventionrelates to such portable systems using Surface Enhanced Ramanspectroscopy in a sensor for detecting the analytes from the exhaledbreath.

BACKGROUND OF THE INVENTION

It is known that exhaled breath is commonly used in alcohol testing andtoday's technology makes it possible to perform on-site breath testingwith legally defensible results using electrochemical sensory. Anemerging technology is using infrared spectroscopy.

However, testing for other illicit drugs of abuse still requires bloodor urine samples. Alternatively specimens comprising hair, sweat or oralfluid could be used. Blood sampling is invasive and requires medicallytrained personnel, why test subject often have to be transported to ahospital for sampling. This is time and effort consuming With long leadtimes the test result will be too old. Urine sampling is consideredintruding on personal integrity and must be done under supervision of anurse or a doctor. Even other issues related to samples and specimentaken from a subject to be tested arise. For instance for blood samples,and especially for urine samples are at risk of the subject exchangingthe samples or using clean samples from another subject to avoid beingdiscovered with traces of illicit drugs.

Result from a study related to this topic and performed on Ireland canbe found in: Results and conclusions from Injury Prevention 2006;12:404-408. doi: 10.1136/ip.2006.013177.33.1% of the drivers under thelegal limit for alcohol tested positive for one or more of the relevantdrugs, and the corresponding figures of drivers over the limit was 14.2.Among drivers who had minimal blood alcohol levels, 67.9% were taking atleast one type of drug. The prevalence of taking drugs reduced steadilyas alcohol concentrations increased, but still remained as high as 11.1%for drivers with blood alcohol concentrations 0.200 mg/100 ml. Beingunder the limit for alcohol, stopped in a city area, stopped between 6am and 4 pm, or 4 pm and 9 pm, and being of a younger age were eachindependently associated with drug positivity.

Conclusions of the study point out the serious need for a readilyavailable drug test in addition to today's alcohol tests. There areimmediate implications for the evidential breath alcohol program and forcheckpoints; in the event of a nil or low alcohol reading beingobtained, a separate blood or urine specimen should be sought foranalysis, which is currently non-routine. However, obtaining blood orurine specimen as a routine test for all drivers in regular trafficcontrols is not a feasible alternative due to the issues pointed outabove.

Another investigation related to this topic is described in: Investigateof the prevalence and characteristics of abusive drug exposure amongnon-fatal motor vehicle driver casualties in Hong Kong. (Hong Kong Med J2010; 16:246-51). The Setting for this study was a Designated traumacentre/regional accident and emergency department in Hong Kong.Investigated subjects were Non-fatal motor vehicle driver casualties whopresented to the trauma centre from 1 Jan. 2007 to 31 Dec. 2007.

Results from drug screening that was performed in 395 injured driversshow 10% of whom tested positive for the drugs of interest. Ketamine wasthe most commonly detected abusive substance (found in 45% of thesubjects). A significantly higher proportion of young drivers (aged <25years) screened positive (odds ratio=2.3; 95% confidence interval,1.0-5.2; P=0.04), with the rate being 21%.

The presence of these drugs in urine was related to the time ofoccurrence of the crash; those occurring between midnight and dawnrevealed a trend towards a higher proportion of casualties testingdrug-positive (odds ratio=2.2; 95% confidence interval, 0.9-5.3;P=0.07). There were no significant differences in the frequency ofpersons testing positive for the screened drugs with respect to gender,class of motor vehicle driven, or the day of the week on which the crashoccurred

This study further supports the urgent need for a convenient, reliableand quick detection of drugs in subjects. An apparatus, system and/ormethod would be advantageous which allows at least for a pre-screeningof subjects to identify subjects under the influence of drugs. Thesesubjects may then further investigated, e.g. by obtaining blood or urinespecimens for analysis.

In addition, there is a need for being able to detect other moleculesfrom exhaled breath as well. For instance biomarker compounds indicativeof various kinds of diseases would be desirable to being able to detect.

However, as there are a multitude of different analytes in exhaledbreath, most in very low amounts or only as traces, it is a challenge tohave a measurement system or method that is sufficiently sensitive todiscern between all these different analytes.

Thus, there is a need to provide a non-invasive, not-specimen basedapparatus, system and/or method for detecting the presence ordetermining the quantitative amount of analytes, in particular at leastone drug substance in a subject.

Hence, an improved apparatus, system and/or method for on-site samplingof a subject for analytes, in particular drug substances is desired.Such an apparatus, system and/or method for sampling the subject forillicit drugs of abuse and/or medical drugs would be desired. Theapparatus, system and/or method should be efficient, non-bulky, userfriendly both for operators and the subject. It should further be notintruding and not invasive. It should preferably be able to discernbetween various analytes.

SUMMARY OF THE INVENTION

Accordingly, embodiments of the present invention preferably seek tomitigate, alleviate or eliminate one or more deficiencies, disadvantagesor issues in the art, such as the above-identified, singly or in anycombination by providing a device, a system, a method, acomputer-readable medium, and a use of these that relates to the use ofa Surface Enhanced Raman Spectroscopy (SERS)-sensor for detecting ordetermining a quantitative amount of an analyte, such as at least onedrug substance, in exhaled breath from a subject in-situ, according tothe appended patent claims.

According to one aspect of the invention, a device is provided, fordetecting the presence or determining a quantitative amount of at leastone drug substance from exhaled breath of a subject in-situ. The devicehaving a light source, a light detector, at least one optical filter,and at least one waveguide, and a collecting surface having at least oneSurface Enhanced Raman Spectroscopy (SERS)-active layer that comprisesat least one SERS-active material. The collecting surface is arranged asan outer surface of the waveguide for contact with said exhaled breath,such that at least traces of at least one drug substance in the exhaledbreath can contact at least one SERS-active layer.

The at least one waveguide is coupled to the light source and thedetector is coupled to the at least one waveguide for a SERS measurementof emitted light from the SERS-active layer. Such that a fraction of thelight from the light source, when sent through said waveguide, istransmitted from the waveguide at least partly through the outer surfaceof the at least one waveguide to the at least one SERS-active layer, anda fraction of a SERS-signal emitted the said SERS-active layer istransmitted back into the waveguide, through the filter and further tothe detector, whereby a Raman shift spectrum is detectable for saidin-situ detecting the presence or determining the quantitative amount ofthe at least one drug substance from said exhaled breath.

The described device thus comprises a sensor that is adapted to obtainat least one Surface Enhanced Raman Spectrum (SERS) from exhaled breath.At least one SERS spectrum can be used to determine the presence of atleast one drug substance. Alternatively, or in addition, the device mayin use determine a quantitative amount of at least one drug substance inexhaled breath.

The collecting surface covered with at least one SERS active layer ispresent on at least a portion of a waveguide only. In some embodiments,the SERS active layer covers the whole waveguide.

The waveguide is preferably an optical fiber, but is not limited to anoptical fiber. In this case, the collecting surface is preferably aradial outside surface along a length of the fiber. The fiber can be inany shape like, straight, bent or coiled, depending on the designrequirements of the system in which the sensor is used in, e.g. thetotal surface area needed to detect the presence of at least one drugsubstance in the collected exhaled breath.

The sensor is adapted to be used with exhaled breath or gases so noliquid solvent is needed to prepare samples for analysis. Hence thesensor can detect volatile and non-volatile analytes in air or exhaledbreath as long as it gives rise to a SERS-signal when in close proximityto a SERS-active surface, substrate, colloid or material.

The physical processes on which the sensor is working are not entirelyinvestigated. However, applicants believe that collected exhaled breathcondensates at the SERS-surface and the small amount of water thenevaporates, thus leaving thousands of analytes from the exhaled breathon the SERS-surface. These analytes then give rise to the emitted SERSspectrum when excited by a light source. In addition, or alternatively,the analytes may be part of an aerosol conveyed by the exhaled breath,which aerosol particles stick to the SERS-surface. Evaporation may alsotake place of aerosol, which then leaves the traces of the analytes onthe SERS-surface for analysis.

The analytes are here drug substances and could be either medical drugsor illicit drugs like, amphetamine, opiates, cocaine, heroin, cannabisetc.

The device could comprise a temperature control element arranged to keepthe collecting surface at a temperature lower than 37 deg C. to providecondensation of vapor in the exhaled breath.

In one embodiment of the invented device the SERS-active layer iscovered by a second layer of a material that is permeable or selectivelypermeable for the at least one drug substance.

By covering the waveguide surface with at least one SERS-active layerand then put at least one layer on top of the SERS-layers that is onlypermeable to a certain type of analytes, here drug substances, or aspecific drug substance, only these analytes that can diffuse throughthe layer will interact with the at least one SERS-layer making itpossible to obtain clearer spectra with less obstacles from otheranalytes that could for example hide important peaks useful whenidentifying different types of drug substances.

Different areas with a SERS-active layer and different layers forselective diffusion of pre-defined analytes may be provided in a singlewaveguide.

The permeable layers could be selected from the group comprisingsilicone polymers and silica and silicone elastomers.

In another embodiment of the invented device, at least one of the atleast one SERS-active layer is a mixture comprising of at least oneSERS-active material and at least one material selected from the groupcomprising silicone elastomers, silicone polymers and silica.

Here a slurry or a mixture of the SERS-active material and at least onepermeable or selectively permeable material is made and used as a layeraround the waveguide. By doing this the layer will be both selective tocertain drug substances and work as a SERS-active layer. This will alsomake the SERS-active layer easier to apply to the fiber and moreresistant.

In yet another embodiment of the invented device, the SERS-active layershave a thickness less than 200 μm, preferably less than 100 μm, morepreferably less than 50 μm, further more preferably less than 20 μm. Thelayers of drug permeable material, if applied, will have a thicknessless than 200 μm, preferably less than 100 μm, more preferably less than50 μm, further more preferably less than 20 μm.

In another embodiment of the invention device the waveguide is a sensorcomprising a plurality of fibres.

Here at least two SERS-active layer covered fibres will be connected tothe same at least one light source and the same detector either as abundle or separated for example within a collection chamber. This willgive a larger SERS-active area that will enhance the recorded spectra.In the case of the fibres being separated, the SERS-active area will bespread over the volume of the collection chamber so that a spectrum of alarger part of the collected volume of exhaled breath will interact witha SERS-active layer.

In another embodiment of the invented device an inlet end of a firstfiber and an outlet end of a second fiber coincide at one end, and alight reflecting mirror is positioned at the first and the second fibresdistal ends.

In this embodiment the light from the light source will be sent throughat least one first fiber with a radial immersive SERS-active layer andthen be reflected by a mirror into at least a second fiber that couldhave a radial immersive SERS-layer and sent to the second fibres outletthat coincides close to the first fibres inlet.

This arrangement will make it easier to have a sensor arranged inside acollection chamber for example a tube.

Another arrangement similar to the above is to have an inlet end and anoutlet end, of a fiber coincide at one end of the fiber, and a lightreflecting mirror is positioned at the distal end of the fiber.

This arrangement work in a similar fashion as the above described twofiber arrangement. But instead of the light being sent from the lightsource through one fiber and back to the detector through a secondfiber, the light will in this embodiment, be sent back and forth throughthe same fiber. Hence the inlet, where the light is to be coupled to thefiber and the outlet where the light to be coupled from the fiber to thedetector, will be the same end of the fiber.

In another embodiment of the invented device the sensor furthercomprises a light pulse splitter interconnected between optical fibresby means of one of a fiber optical circulator and an optical coupler.

In some embodiments the device comprises a Bragg grating for fiberspectrometer application. The object of this embodiment is to provide animproved photonic fiber detector arrangement for determining theconcentration of at least one substance in a fluid, e.g. a specificsubstance in a specific mixture. Especially the immunity of the Braggsensor against electric and magnetic fields may be advantageous incertain areas of application. There is no electrical energy at the siteof the measurement. These sensors may be used in areas with explosiverisk.

In yet another embodiment of the invented device the optical filter isused for selecting a wavelength region having peaks related to aspecific type of drug substance.

By introducing different bandpass-filters between the outlet end of thewaveguide and the detector it is possible to both get a higherresolution since less wavelength will be recorded on the same detectorarray. This will increase the possibilities of detecting a drugsubstance with known SERS-peaks within the wavelength range of thebandpass-filter. Multiple bandpass-filters can be used consecutiveeither to obtain a high resolution for a large wavelength range byadding the recording spectra or by selecting filter that each filter hasa wavelength range with known peaks that can be used to characterize atleast one specific drug substance.

The analytes may comprise alcohol, thus allowing for an addition ofcombined detection of alcohol and illicit drugs by a single deviceoperable on site where the breath is exhaled.

According to another aspect of the invention, a system for detecting thepresence or determining the quantitative amount of at least one drugsubstance from exhaled breath of a subject in-situ. The system comprisesthe invented sensor device, a collecting chamber, a mouth-piece or abreathing mask, a control unit and a user interface. The mouthpiece isarrangeable in fluid connection to the sampling chamber to direct theexhaled breath from the subject to the sampling chamber. The mouthpiecemay be a unit for single use that is removable from the system. Thecontrol unit is adapted to analyze obtained spectrum and to send anindication related to a presence of a drug and/or a concentrationthereof in the exhaled breath through the user-interface to the subject.

The subject will here exhale breath through the mouthpiece or mask intothe collecting chamber comprising at least one inlet and one outlet. Thechamber could have any size or shape but is preferably a tube. At leastone SERS-sensor device is arranged inside the collecting chamber tointeract with the exhaled breath. The SERS-sensor will record at leastone spectrum that will be analyzed. Analysis of the spectrum may be madefor example based on multivariate data analysis for example PartialLeast Square (PLS), Neural Networks or fuzzy logic. The analysis is notlimited to these methods since there are other methods that could beadapted to be used in embodiments of the invention by a person skilledin the art. The control unit, which carries out the analysis, mayinteract with the subject using a user interface. This could be by asignal like a red lamp if a drug is detected and a green lamp if thesubject passes the exhaled breath test. Alternatively, or in addition,the user notification could also be a number giving the concentration inrelation to for example a volume of exhaled breath and/or compared tothe amount of carbon dioxide and/or water. The system could alsocomprise a sensor for measuring the flow of exhaled breath. This couldbe used to se if the right amount of exhaled breath is obtained or thatthe subject a breathing correctly. The preferred way is to take an extradeep breath. Since the preferred exhaled breath to measure on is the airfrom the lung the sensor can be used to tell the control unit when tostart to measure to avoid measuring on shallow exhaled breath from themouth and the throat.

The user interface can also be used to communicate with the user whenthe system is ready to be used for example after the system has staredup or initial tests have been carried out for example recording at leastone background spectrum or measured against internal standards.

The invented system or SERS-sensor could be used for a wide range ofapplications including: detecting the presence or determining thequantitative amount of at least one drug substance from exhaled breathof a subject in-situ; such as a drug test at an emergency hospital or inan ambulance; such as at a school or a work place.

According to another aspect of the invention, a device for detecting thepresence or determining a quantitative amount of an analyte, such as atleast one drug substance, from exhaled breath of a subject in-situ isprovided. The device comprises a light source, a light detector, and acollecting surface having at least one Surface Enhanced RamanSpectroscopy (SERS)-active layer that comprises at least one SERS-activematerial. The collecting surface is arranged as a surface at said devicefor contact with said exhaled breath, such that at least traces of saidat least one drug substance in said exhaled breath can contact saidSERS-active layer, and wherein said surface is arranged on top of said(SERS)-active layer or wherein said (SERS)-active layer comprises amixture comprising at least one SERS-active material and a material thatis selective permeable for said analyte. The light source and saiddetector are arranged to for a SERS measurement of emitted light fromsaid SERS-active layer, such that a fraction of the light from saidlight source, when sent to said SERS-active layer, is transmitted atleast partly through said outer surface to said at least one SERS-activelayer, and a fraction of a SERS-signal emitted from said SERS-activelayer is transmitted to said detector, whereby a Raman shift spectrum isdetectable for said in-situ detecting the presence or determining thequantitative amount of said analyte, comprising at least one drugsubstance, from said exhaled breath.

This arrangement may be made planar, i.e. the collective surface isplanar, receiving light from the light source and reflecting SERS-signallight back to the detector for spectral analysis.

According to yet another aspect of the invention, a method is providedfor detecting the presence or determining the quantitative amount of atleast one drug substance from exhaled breath of a subject in-situ. Themethod comprises the steps of:

-   -   providing a sensor according to the aforementioned description;    -   collecting an exhaled breath sample from a subject;    -   making contact between said exhaled breath sample and said        SERS-active layer of said device;    -   recording at least one spectrum from light emitted from said        SERS-active layer;    -   analyzing said at least one spectrum to detect the presence or        determining the quantitative amount of at least one drug        substance in said exhaled breath sample.

According to a further aspect of the invention, a method is provided,for detecting the presence or determining the quantitative amount of atleast one drug substance from exhaled breath of a subject in-situ,comprising providing and using a system according to the aforementionedaspect. The method comprises the steps of:

-   -   recording at least one background spectrum using the        SERS-sensor;    -   collecting an exhaled breath sample in a chamber;    -   recording a spectrum of the exhaled breath sample using said        SERS-sensor;    -   analyzing said spectrums using the control unit; and    -   giving said subject an indication using a user interface.

According to a further aspect of the invention, a computer-readablemedium having embodied thereon a computer program for processing by acomputer is provided. The computer program comprises a plurality of codesegments for analyzing at least one spectrum to detect the presence ordetermining the quantitative amount of at least one drug substance insaid exhaled breath sample.

Embodiments avoid and do not involve the use of liquid solvents forpreparing the breath samples for the SERS-measurement.

Use of an SERS-active substrate or layer, or of the device, system ormethod of the afore mentioned aspects of the invention are provided fordetecting the presence or determining the quantitative amount of analytefrom exhaled breath of a subject in-situ.

The analyte may comprise at least one drug substance, and/or a biomarkercompound indicative of a disease of said subject.

Use of an SERS-active substrate or layer, or of the device, system ormethod of the afore mentioned aspects of the invention are provided as adrug lock unit for passage systems based on exhaled breath directed ontosaid SERS-active substrate. A detected drug substance in exhaled breathof a subject may provide a suitable signal for a control unit of saidpassage system for said locking. The use may comprise locking thepassage systems, such as at airports, work places, hospitals, jails,etc.

Use of an SERS-active substrate or layer, or of the device, system ormethod of the afore mentioned aspects of the invention are provided as adrug test at an emergency hospital or in an ambulance based on exhaledbreath directed onto said SERS-active substrate.

Use of an SERS-active substrate or layer, or of the device, system ormethod of the afore mentioned aspects of the invention are provided as adisease diagnostic system based on exhaled breath directed onto saidSERS-active substrate, wherein diagnosis of a disease of said subject isbased a detected biomarker compound indicative of a disease of saidsubject.

Further embodiments of the invention are defined in the dependentclaims, wherein features for the second and subsequent aspects of theinvention are as for the first aspect mutatis mutandis.

Embodiments provide for in-situ measurements providing measurementresults directly from exhaled breath.

Identification of molecules is thus detectable based on exhaled breathsamples. Some embodiments allow for quantitative determination of thechemical compounds found in exhaled breath.

Some embodiments provide for sufficient sensitivity to discern betweendifferent analytes in exhaled breath samples. Measurements systems andmethods that are selectively providing Raman spectra for pre-definedchemical compounds or analytes in exhaled breath are provided.

It should be emphasized that the term “comprises/comprising” when usedin this specification is taken to specify the presence of statedfeatures, integers, steps or components but does not preclude thepresence or addition of one or more other features, integers, steps,components or groups thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects, features and advantages of which embodiments ofthe invention are capable of will be apparent and elucidated from thefollowing description of embodiments of the present invention, referencebeing made to the accompanying drawings, in which

FIG. 1 is a schematic illustration that shows an embodiment of theSERS-sensor with a first SERS-active layer and an optional analytepermeable or analyte selectively permeable layer;

FIG. 2 is a schematic illustration that shows another embodiment of theSERS-sensor similar to the previous but with a SERS-active layer being aslurry or a mixture of at least one SERS-active material and at least onanalyte permeable material;

FIG. 3 is a schematic illustration that shows an alternative arrangementof the SERS-sensor;

FIG. 4 a is a graph that shows three Raman spectra;

FIG. 4 b is a graph that shows two SERS spectra of spiked exhaledbreath, whereof one is spiked with amphetamine;

FIG. 5 is a schematic illustration illustrating an embodiment of asystem based on a SERS-sensor;

FIG. 6 is a flow-chart illustrating a first method for using aSERS-sensor;

FIG. 7 is a flow-chart illustrating a second method for using aSERS-sensor system;

FIG. 8 is a flow-chart illustrating the code segments of acomputer-program;

FIG. 9 a is a schematic illustration of an optical filter in form of aBragg sensor; and

FIG. 9 b is a schematic illustration illustrating an embodiment of asystem based on a SERS-sensor and a Bragg sensor unit for readout.

DESCRIPTION OF EMBODIMENTS

Specific embodiments of the invention will now be described withreference to the accompanying drawings. This invention may, however, beembodied in many different forms and should not be construed as limitedto the embodiments set forth herein; rather, these embodiments areprovided so that this disclosure will be thorough and complete, and willfully convey the scope of the invention to those skilled in the art. Theterminology used in the detailed description of the embodimentsillustrated in the accompanying drawings is not intended to be limitingof the invention. In the drawings, like numbers refer to like elements.

In an embodiment of the invention according to FIG. 1 a part of aSERS-sensor 10 is shown. The sensor 10 is based on obtaining at leastone Surface Enhanced Raman Spectrum (SERS) from exhaled breath. SERS isa surface technology, described in more detail below, enhancing Ramandetection technology.

Thus embodiments of the SERS sensor allow for detection of one or moresubstances, even when present in very low amounts or concentrations.

Returning to FIG. 1, the sensor 10 is provided in form of a waveguide 12having at least one SERS-active layer 14. The waveguide 12 may be anoptical fiber.

In the embodiment, the SERS-active layer 14 is arranged outside of thewaveguide at the circumference of the waveguide 12 and is extendinglongitudinally along a portion of the outer surface thereof.

Each SERS-layer 14 comprises at least one SERS-active material. For eachSERS-layer a different SERS-active material may be provided.

The SERS-active material should be of a metal material. The metal ispreferably comprised in the group of gold or silver or copper orPlatinum or palladium or any mixtures thereof. The SERS-active layer 14could either be made of colloids or being a substrate similar toKlarite® The SERS-active material is provided as nanoparticles ornanoparticle aggregates, thus providing the SERS-active layer 14 with ananoscale roughness.

To achieve a measurable effect by a SERS-based measurement system, asdescribed below, a drug substance 15 found in exhaled breath needs tocome into contact with the metal with a nanoscale roughness on theSERS-layer 14 surface, or with similar arrangements of the SERS activenanoparticles. The substance then determines the Raman spectrumregistered by a light detector 17, which spectrum is emitted from theSERS-layer upon excitation from light of the light source 11.

The shape and size of the metal nanoparticles or nanoparticlesaggregates or the roughness of the surface strongly affects the strengthof the enhancement because these factors influence the ratio ofabsorption and scattering events.

In this embodiment a SERS-active layer 14 could optionally be at leastover a surface portion thereof be covered, coated or encapsulated by anouter, encapsulating layer 13. The outer layer 13 may be made of eithersilicone polymers and/or silica and/or silicone elastomers or similar.The material that the encapsulating layer 13 is made of is chosen to bepermeable for certain pre-defined analytes 15. The encapsulating layer13 could therefore act as a barrier for unwanted analytes that shows alower diffusion through the layer, thus work as a pre-selecting filterto select only the drug substances 15 of interest. Hence a clearerspectrum without unwanted peaks that could be an obstruction could beobtained. The coating 13 may reduce noise in the SERS-measurement.

Thus a SERS-sensor is provided that is configured for measurement ofspecific pre-defined drugs in exhaled breath, whereby the measurement isprovided with an advantageous signal to noise ratio.

An alternative SERS-sensor 20 is illustrated in FIG. 2. The SERS-sensorhas been produced by another method for applying the SERS-material ontothe waveguide-surface 22, which result can be seen in FIG. 2. Here aslurry or a mixture of the SERS-material and a selectively permeablematerial are provided instead of a separate SERS-active layer and apre-selecting filter material coating. The slurry or mixture may e.g.comprise the SERS-active nanoparticles and silicone polymers and/orsilica and/or silicone elastomers and are provided for use as a singlelayer 23 on the waveguide 22 circumference.

The waveguide 22, preferably is a fiber, as mentioned above. Morepreferably the fiber is a mono-mode fiber.

The waveguide 22, 12 is arranged to have an inlet connected to a lightsource 11. The light source 11 could here be selected from a listcomprising: lasers, laser diodes, light emitting diodes, hollow cathodelamps, Xenon arc lamps, deuterium lamps, metal halide, and plasma lamps.

When a fiber is used, it could have a cladding or the SERS-active layer14, 23 could be used as a cladding. A criterion when providing the fiber12, 22 with a cladding layer is that light can be transmitted or coupledfrom the core of the fiber 12, 22 to the surrounding SERS-active layer14, 23. The light thus diverted out of the fiber core is then providedto excite the SERS-active layer 14, 23 of the outer cladding. Theemitted light from the SERS-active layer 14, 23 is then transmitted orcoupled back into the same fiber 12, 22 and spectrally analyzable toprovide the drug measurement result. For a Multi-mode or graded-indexfiber 12, 22 this can be done my allowing a part of the intensity of thereflected light between the core and the cladding to transmit to theSERS-active layer 14, 23. For a mono-mode fiber 12, 22 the evanescentfield could be transmitted and used to excite to the SERS-active layer14, 23. This could for example be done by modifying the cladding eitherby matching the refractive index of the cladding closer to the core orby making it thinner. For some embodiments it would even be an advantageto use the SERS-active layer 14, 23 as a cladding.

The light source 11 emits preferably light in the wavelength rangebetween 0.3 and 1.5 μm but preferably in the range 0.5-1.2 μm, and evenmore preferably in the range 0.75-1.1 μm.

At the opposite end of the fiber 12, 22, from the inlet, is an outletarranged in connection to an optical filter 16 and the light is thenfurther directed onto a detector 17.

The filter 16 is used to remove the wavelength of the light source 11.The filter 16 may in addition or alternatively be used to limit thewavelength range to include only a wavelength range with peaks known tobe strong for a specific drug substance or drug substances. By puttingdifferent filters 16 between the fiber 12, 22 and the detector 17 in asequence after each other, different parts of the wavelength range canbe obtained and recorded. Wherein each wavelength range, obtained usingthe optical filters 16, comprises information in the form of peaks, forat least one drug substance 15. In this manner, background noise isreduced and the measurement made robust and reliable.

The detector 17 may in embodiments be selected from the list comprising:photocells, photodiodes, phototransistors, CCD, CMOS, photoelectrictubes and photomultipliers.

A further embodiment of the invention is illustrated in FIG. 3 in formof a backscattering arrangement. A SERS sensor 30 is provided having oneor more SERS-active layers 35. The SERS-layers 35, and if desired thedrug substance permeable layers, are applied to the waveguide 32 andprovided as described above. Here the detector 17, the at least oneoptical filter 16 and the light source 11 are located at the same sideof the fiber 32 where light is both coupled in and out of the fiber 32.Thus one end of the waveguide 32 is both the excitation light inlet andthe SERS layer reflected light outlet.

At the distal end of the waveguide a mirror 36 or other highlyreflective material can be placed to reflect the light back into thefiber 32. This will enhance the signal further since the SERS-layer 35will be exposed to the excitation light twice.

In some embodiments, said at least one waveguide is at least one opticalfiber. The optical fiber is for instance made of silica glass or asuitable polymer. The fiber may be bent. In addition, the fiber may becoiled. Such embodiments provide for compact sensor arrangements withlarge available collecting surfaces.

The sensor device may comprise a plurality of fibres.

The device may further comprise a light pulse splitter interconnectedbetween optical fibres by means of one of a fiber optical circulator andan optical coupler.

An example is illustrated in FIG. 9 a.

In some embodiments the device comprises a Bragg grating for fiberspectrometer application.

A fiber Bragg grating (source: Wikipedia) is a type of distributed Braggreflector constructed in a short segment of optical fiber that reflectsparticular wavelengths of light and transmits all others. This isachieved by adding a periodic variation to the refractive index of thefiber core, which generates a wavelength specific dielectric mirror. Afiber Bragg grating can therefore be used as an inline optical filter toblock certain wavelengths, or as a wavelength-specific reflector.

The scanning filter in front of the detector is comprised of two mainbuilding blocks:

-   -   An acoustic-optic actuator device and    -   A fiber Bragg grating

As can be seen in FIG. 9 b, a SERS-based measurement system 34, asdescribed below, an analyte 37, such as a drug substance found inexhaled breath needs to come into contact with the metal with ananoscale roughness on the SERS-layer 35 surface, or with similararrangements of the SERS active nanoparticles. The substance thendetermines the Raman spectrum registered by a light detector, whichspectrum is emitted from the SERS-layer upon excitation from light ofthe light source 33. A waveguide based system is shown, similar to thatof FIG. 3 including a mirror 35. Instead of a filter at the detector,the Bragg grating based readout improvement is provided as describerbelow.

An electronic signal generator drives the acoustic actuator thatlaunches a short, longitudinal acoustic pulse into the core of thefiber. The pulse traverses the fiber at a great speed and passes over along, chirped fiber Bragg grating. The grating is characterized by beingreflective for a certain wavelength at a well-defined position along thegrating. As the acoustic pulse passes over the grating, a local andsuperimposed disturbance of the core's refractive index is established.By generating a disturbance of well-known character, a narrowtransmission window with high sidemode suppression is created to allow acertain wavelength to pass through the grating. As the pulse moves overthe chirped grating, the center wavelength of the transmission window isshifted and a scan is performed.

The Bragg based readout improvement may also be combined with other SERSsensors having different or no waveguide arrangements.

In some embodiments the collecting surface is arranged for collecting abreath condensate or aerosol with said drug. The sensor device maycomprise a temperature control element that is arranged to keep saidcollecting surface at a temperature lower than 37 deg C. to providecondensation of vapor in said exhaled breath. Other surface parts of thesensor device may be heated to a temperature higher than 37 deg C. toavoid condensation of vapor in said exhaled breath. This allows for acontrolled condensation at the collecting surface.

In another embodiment (not shown), an arrangement is provided without awaveguide having a SERS-active layer. This may be a planar arrangementof the SERS-active layer. Waveguides without SERS-active layer, such asoptical fibres may be used merely for conveying light from the lightsource and/or to the detector.

In more detail, a device for detecting the presence or determining aquantitative amount of an analyte, such as at least one drug substance,from exhaled breath of a subject in-situ is provided. The devicecomprises a light source, a light detector, and a collecting surfacehaving at least one Surface Enhanced Raman Spectroscopy (SERS)-activelayer that comprises at least one SERS-active material.

The collecting surface is arranged as a surface at said device forcontact with said exhaled breath, such that at least traces of said atleast one drug substance in said exhaled breath can contact saidSERS-active layer.

The said surface may be arranged on top of said (SERS)-active layer.Alternatively, or in addition, said (SERS)-active layer may comprise amixture comprising at least one SERS-active material and a material thatis selective permeable for said analyte.

The light source and said detector are arranged to for a SERSmeasurement of emitted light from said SERS-active layer, such that afraction of the light from said light source, when sent to saidSERS-active layer, is transmitted at least partly through said outersurface to said at least one SERS-active layer. A fraction of aSERS-signal emitted from said SERS-active layer is transmitted to saiddetector, whereby a Raman shift spectrum is detectable for said in-situdetecting the presence or determining the quantitative amount of saidanalyte, comprising at least one drug substance, from said exhaledbreath.

This arrangement may be made planar, i.e. the collective surface isplanar, receiving light from the light source and reflecting SERS-signallight back to the detector for spectral analysis.

In FIG. 4 a, a spectrum from a test on Klarite® is shown, see the curve42, wherein X is the wavenumber in cm⁻¹ and Y is The Raman intensity incps. Klarite® substrates are commercially available from RenishawDiagnostics, see http://www.renishawdiagnostics.com/en/12409.aspx. Inmore detail, the graph 40 illustrates a SERS spectrum obtained fromdetection of amphetamine by Raman spectroscopy utilizing irradiationlight 785 nm. Normal (not enhanced) Raman spectrum of pure amphetaminepowder 41 shows many peaks that can be used for identification, forexample those positioned at 621, 1004, 1030 and 1207 cm⁻¹. SERS spectraare also obtained for diluted amphetamine solutions; one 42 correspondsto amphetamine adsorbed on gold nanostructured Klarite surface and one43 corresponds to 1 μm amphetamine solution containing SERS active goldnanoparticles. A droplet of 2 μL amphetamine solution of 1 μM was addedto Klarite surface and after solvent evaporation a laser beam wasfocused on a micrometer sized spot to generate a characteristic spectrum42. The amount of the drug that gives rise to spectrum 42 is estimatedto be 0.3 pg.

The SERS spectra 40 of the drug substances of FIG. 4 a shows a series ofunique, high intensity peaks which give a fingerprint of the molecularstructure of the tested drug substance. This feature of SERS allows theidentification of unknown compounds in addition to their detection atlow concentrations. Furthermore, the band positions and relativeintensities of the SERS-spectra match closely to the bulk Raman signal.

Surface enhanced Raman spectroscopy (SERS), is used to identifyamphetamine in exhaled breath. Using the SERS surface Klarite®,measurements of very low amounts, down to a few pg, of amphetamine havesuccessfully shown that it is possible to measure the low concentrationof amphetamine expected to be found in exhaled breath. Detection ofamphetamine in exhaled breath is difficult because of interferingbackground signals from bio molecules in breath samples and impuritiesin solvents. The data indicates that it is possible to measureamphetamine in exhaled air, using SERS, from drug users if it ispossible to reduce the background noise.

A multivariate data analysis was used, where the first derivates ofunprocessed spectra were used. Ten breath samples without amphetamine,four breath samples spiked with 20-25 pg and 2 breath samples from drugusers where used to build the model. The same samples and four moresamples spiked with 100 pg amphetamine were used to calculate a Partialleast square (PLS) model. Results indicated clearly that multivariatedata analysis is suitable for separating persons under the influence ofdrugs from persons not having consumed drugs.

In FIG. 4 b, some further SERS-spectra from a test on Klarite® areshown. The spectra shows two spectrum one of exhaled breath withoutamphetamine and one spiked with 20 pg. The spiked spectra has a clearlyvisible peaks related to amphetamine.

In FIG. 4 b SERS spectra are shown of exhaled air adsorbed on a filter.Both filters where eluted with organic solvents and one of the sampleswhere spiked with 20 pg amphetamine (red spectrum). In conjunction withSERS measurement the samples where dissolved in pure deionized water anda droplet of 2 μL was added to a naked SERS active surface (Klarite).Before laser illumination of 785 nm (3 mW) the liquid droplet wasevaporated and exhaled substances were adsorbed on the SERS activesurface in dry condition. The spectra were performed on a HORIBA LabRamHR800 Raman spectrometer. It is obvious the Raman signatures are ofcomplex nature where many peaks originating from different species areoverlapping. However, FIG. 4 b is indicative that in principle one coulddistinguish between drug containing and not containing exhaled air. Oneway is to build up a multivariate data model where a relevant trainingset is crucial. Most important spectral region in such patternrecognition working model depends on the target molecules but mostly itis lying in range of 600-1800 cm⁻¹. Sometimes high frequency region isof importance around 2300 and 3000 cm⁻¹. FIG. 4 b also says that it ifthe selectivity of the SERS surface is increased towards certain drug itshould be much easier to judge any presence of target molecules. Forexample this could be achieved by mixing a polymeric layer with SERSactive surfaces (or nanoparticles) possessing suitable physicochemicalproperties for diffusion certain class of analytes of interest.

FIG. 4 supports clearly the selectivity of SERS active surfaces fordetecting certain chemical compounds from exhaled breath. This applieseven though only very small amounts or traces of the specific compoundare present in the exhaled breath. In addition, it has been shown thatdetection of traces of certain specific chemical compounds in exhaledbreath is provided although many other chemical compounds are present inthe exhaled breath and it would have been expected that measurementresults were influenced. However, it was shown that measurement resultsfor the desired specific compound under investigation are reliable andnot disturbed by other compounds present in the in exhaled breath.Multiple SERS surfaces that are prepared to be selective for differentchemical compounds may be combined to provide a multi parameter systemin a single compact system.

FIG. 5 is a schematic chart illustrating a system 50 based on theinvented sensor 53. A subject to be tested exhales into a mouth-piece ora mask 51, that is in communication with a collection chamber 52 via atleast one inlet 57. The bold arrows in FIG. 5 illustrate a flow of theexhaled breath.

Optionally the inlet could be provided with a flow sensor 58 be arrangedfor measuring the flow of the exhaled breath and send the information tothe control unit 54. Thus the flow over time and thus the volume ofexhaled breath may be determined based on an output signal of the flowsensor 58. Hence, concentrations of substances in the exhaled breath maybe determined

In the collection chamber is at least one sensor 53 arranged forrecording at least on SERS-spectrum. In use, the exhaled breath exitsthe chamber through the collection chamber's 52 at least one outlet 56.The at least one recorded spectrum is sent to the control unit 54 to beanalyzed. The obtained result is prompted to the operator to subject viaa user interface 55.

The user-interface 55 could also be used to tell the subject when thesystem is ready to be used or if any error has appeared, e.g. during themeasurements or during the system's initialization phase.

FIG. 6 is a flow-chart illustrating the method 60 for using theSERS-sensor 61. First, the SERS-sensor 61 is provided. In the next stepan exhaled breath sample is collected from a subject 62. This is done byexhaling breath onto the sensor 61. This maybe done directly or via amouthpiece or a breathing mask. The next step is to make sure that thedrug substances appears close enough 63 to the SERS-active layer so thatthe enhancement of the Raman spectra can occur.

It is also preferable if the exhaled breath can be in a highconcentration since that will increase the concentrations of drugsubstance particles close to the at least one SER-active layer. This canbe done by arranging the sensor 61 in a collecting chamber. When the atleast one drug substance to be determined is in close proximity 63 to aSERS-active layer at least one spectrum can be recorded 64 using thesensor 61. The at least one spectrum is in use analyzed and during thisanalysis it can be determined if a drug substance is present and/or whatdrug substance is present and/or the concentration (quantitative amount)of the drug substance is determined.

FIG. 7 shows a flow-chart illustrating a method 70 for detecting atleast one drug substances in exhaled breath using a system comprisingthe aforementioned SERS-sensor.

The first step is an optional step of recording at least on backgroundspectrum using the SERS-sensor 71.

The next step is to collect an exhaled breath sample in a collectionchamber 72. The collection chamber can have any shape or size but ispreferable a small tube with a small volume having the sensor arrangedinside the tube. Hence there will be a high flow of exhaled breaththrough the tube leading to a concentration of drug particles around thesensor.

The next step is recording at least one SERS-spectrum 73 during acertain period of time. This period is determined so that a highsignal-to-noise is achieved related to the time it takes for a subjectto empty his/her lungs. The recorded spectrum is analyzed 74 using asoftware that is run on or part of a control unit 54. The Control unitis then prompting the subject with the results 75 via a user-interface.The user-interface could here be a red and a green lamp, a small displayor the built in TFT screen of a passage system or a computer screen.

FIG. 8 is a flow-chart illustrating the code segments of thecomputer-program. 80 is a computer-readable medium with a computerprogram 81 having a plurality of code segments for analyzingspectral-data 82 and determining if a drug substance is presence in theexhaled breath.

The detectable drug substance may be including in the non-exhaustivelist comprising Amphetamines, ecstasy, Cannabis (THC and cannabinoids),Opiates heroin/morphine, 6-AM), Cocaine, Benzodiazepines, Propoxyphene,Methadone, Buprenorphine, Tramadol, LSD, Designer/Internet drugs,Kathinon, GHB, Meprobamat, Z-drugs, Tryptamines, Anabolic steroids,Alcohol/markers but are not limited to these. Other illicit drugs notincluded in the list could also be detectable due to similarinterchanges with the human body as the above mentioned illicit drugsubstances.

A practical implementation of the innovation is a handheld mobile drugtesting apparatus.

The present invention has been described above with reference tospecific embodiments. However, other embodiments than the abovedescribed are equally possible within the scope of the invention.Different method steps than those described above, performing the methodby hardware or software, may be provided within the scope of theinvention. SERS-layer described as present on the outside of waveguidesmay likewise be present on an interior surface of a hollow waveguide,etc. The different features and steps of the invention may be combinedin other combinations than those described. The scope of the inventionis only limited by the appended patent claims.

The invention claimed is:
 1. A method of recovering exhaled nonvolatiledrug compounds from a filter, comprising: providing said filtercomprising an exhaled aerosol comprising said nonvolatile drugcompounds; eluting said nonvolatile compounds from said filter with anorganic solvent to form a sample; evaporating at least a portion of saidsample on a SERS-active surface; recording at least one SERS-spectrum ofsaid evaporated portion of said sample using SERS-technique.
 2. Themethod according to claim 1, performing an analysis of the content insaid sample from said at least one recorded SERS-spectrum.
 3. The methodaccording to claim 1, comprising identifying said nonvolatile drugcompounds from said SERS-spectra using a multivariate data model.
 4. Themethod according to claim 2, performing an analysis of the content insaid sample from said at least one recorded SERS-spectrum.
 5. The methodaccording to claim 1, comprising facilitating analysis by modifying saidSERS-active surface to be selective towards certain drug compounds. 6.The method according to claim 5, comprising mixing a polymeric layerwith nanoparticles to obtain a SERS-active surface.
 7. The methodaccording to claim 5, wherein said SERS-active surface is possessingsuitable physiochemical properties for diffusion certain class of drugcompounds.
 8. The method according to claim 5, comprising adding apermeable layer selected from a group comprising silicone polymers,silica or silicone-elastomers to said SERS-active surface.
 9. The methodaccording to claim 8, wherein said added layer is covering, coating orencapsulating said SERS-active surface.
 10. The method according toclaim 6, comprising adding a permeable layer selected from a groupcomprising silicone polymers, silica or silicone-elastomers to saidSERS-active surface.
 11. The method according to claim 5, comprisingmixing of at least one SERS-active material and at least one materialselected from a group comprising silicone elastomers, silicone polymersor silica to form said SERS-active surface.
 12. The method according toclaim 6, comprising mixing of at least one SERS-active material and atleast one material selected from a group comprising silicone elastomers,silicone polymers or silica to form said SERS-active surface.
 13. Themethod according to claim 1, comprising adding pure deionized water tothe sample.
 14. The method according to claim 1, wherein detectablenonvolatile drug compounds is included in the list comprising:Amphetamines, ecstasy, Cannabis (THC and cannabinoids), Opiatesheroin/morphine, 6-AM), Cocaine, Benzodiazepines, Propoxyphene,Methadone, Buprenorphine, Tramadol, LSD, Designer/Internet drugs,Kathinon, GHB, Meprobamat, Z-drugs, Tryptamines and Anabolic steroids.15. A non-transitory computer-readable medium comprising a computerprogram configured for said recording at least one SERS-spectrumaccording to claim 1 and said performing an analysis according to claim2, wherein said computer program comprises code segments for: recordingat least one SERS-spectrum according to claim 1; analyzing said at leastone SERS spectrum according to claim 2; and reporting a presence ordetermining a quantitative amount of nonvolatile drug compounds, in saidexhaled breath sample.
 16. The non-transitory computer-readable mediumof claim 15, further comprising a code segment for identifying saidnonvolatile drug compounds from said at least one SERS-spectrum using amultivariate data model.
 17. A method of detecting a nonvolatile drugcompound present in exhaled breath, the exhaled breath being absorbed ona filter, the method comprising: eluting said nonvolatile drug compoundfrom said filter with an organic solvent to form a sample; evaporatingat least a portion of said sample on a SERS-active surface; recording atleast one SERS-spectrum of said evaporated portion of said sample usingSERS-technique.
 18. The method of according to claim 17, furthercomprising capturing an exhaled aerosol from the exhaled breath in saidfilter.
 19. The method according to claim 18, further comprising asubject exhaling into said filter.